There are a number of materials, which have been identified as posing significant health hazards to personnel exposed to or coming in contact with such materials.
For example, asbestos has been well-known and recognized for its insulation and fireproof properties and, as a result was widely used as an insulation and/or fireproofing material. In spite of these excellent insulation and fire retardant characteristics, it has been established that airborne asbestos fibers, and other fine particles of asbestos are the cause of a serious disease known as asbestosis as well as causing a type of cancer known as mesothelioma.
Due to the serious health hazards, which may result from continued exposure to asbestos as well as other materials that include fine particulate contaminants, significant efforts have been made, especially throughout the United States, to remove or abate asbestos from buildings and/or any other structures employing asbestos as an insulating and/or fire retardant material. Due to the serious health hazards posed by asbestos, detailed government regulations have been provided to dictate the handling and removal of asbestos as well as the protective measures, which have been promulgated to insure the safety of personnel involved in the removal and/or abatement of such hazardous material as well as isolation of the areas being decontaminated to prevent exposure to uncontaminated areas as a result of the removal and/or abatement of asbestos from contaminated areas.
One conventional apparatus and technique for asbestos abatement and/or removal is disclosed in U.S. Pat. No. 4,604,111, in which an enclosure is created to isolate the region in which asbestos is to be removed. The space is sealed by plastic sheets or the like, an air inlet is provided for the enclosed space to permit air to be drawn into the region, and a filtration unit is employed to provide an air outlet so that fibers and particulate are collected in the filtration unit. A negative air system is utilized to assure that all of the air in the enclosed space is under pressure to leave. However, air only leaves through the filtration unit covering the air outlet to collect dangerous fibers and other particulate.
In order to gain access to the region to be decontaminated, an entrance port is provided. The entrance is selectively sealed by a "flap seal" typically comprised of a plastic sheet, and is designed to form a one-way closure with the aforementioned opening so that air is normally drawn into the enclosed region so long as a negative pressure condition is maintained, and whereby the flap seals the opening as a result of failure or sudden loss of the negative pressure to prevent airborne matter from leaving the enclosed region other than through the filter.
The aforementioned U.S. Pat. No. 4,604,111 also discloses that it is conventional to provide a decontamination unit in close proximity to the contaminated region, such decontamination unit being typically referred to as a "decon" unit, which is conventionally comprised of three adjoining chambers including a "dirty room", shower and clean room enabling personnel to leave the contaminated area and enter into the decon unit to be vacuumed off, and remove protective garments and masks in the dirty room, shower in the shower unit, and dress in the clean room in a manner so that the decon unit isolates the contaminated region. The region connecting the contaminated work area and the decon unit is typically short in length and is isolated from adjacent regions for the protection of the public.
Employing the above technique in job sites such as multi-story, high rise office buildings, factories or the like, necessitates the provision of a decon unit at each work area. In the event that the floor space of each floor is quite large, decon units are typically required at two or more locations on each floor depending on locations of the work areas when employing the techniques of U.S. Pat. No. 4,604,111, thus significantly increasing the capital costs for equipment employed at such job sites.